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Quotes. "When written in Chinese the word 'crisis' is composed of two characters. One represents danger, and the other represents opportunity.“ John Kennedy. Taxonomy (Classification). Microbiology 2314. Taxonomy.
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Quotes • "When written in Chinese the word 'crisis' is composed of two characters. One represents danger, and the other represents opportunity.“ John Kennedy
Taxonomy (Classification) Microbiology 2314
Taxonomy The science of biological classification, by grouping organisms with similar characteristics.
Three Interrelated Parts of Taxonomy • Classification Arrangement into groups • Nomenclature Assignment of Names • Identification Determining Identity
Classification Versus Identification • Classification answers questions of the sort: How is this fungus related to other fungi? • Identification addresses the more immediate question: What's the name of the specimen in front of me?
Three Major Domains • The three-domain system is a biological classification introduced by Carl Woese in 1990 that divides cellular life forms into archaea, bacteria, and eukaryote domains.
In particular, it emphasizes the separation of prokaryotes into two groups, originally called Eubacteria (now Bacteria) and Archaebacteria (now Archaea). • Woese argued that, on the basis of differences in 16S rRNA genes, these two groups and the eukaryotes each arose separately from an ancestor with poorly developed genetic machinery, often called a progenote. To reflect these primary lines of descent, he treated each as a domain, divided into several different kingdoms.
Archaea Domain • Prokaryotic, no nuclear membrane, distinct biochemistry and RNA markers from eubacteria, possess unique ancient evolutionary history for which they are considered some of the oldest species of organisms on Earth; traditionally classified as archaebacteria; often characterized by living in extreme environment. • Kingdom ArchaebacteriaExample: • Methanogens – metabolize hydrogen and carbon
Bacteria Domain • Prokaryotic, no nuclear membrane, traditionally classified as bacteria, contain most known pathogenic prokaryotic organisms, studied far more extensively than Archaea • Kingdom EubacteriaExample: • Cyanobacteria – photosynthesizing bacteria
Eukarya Domain • Eukaryotes, nuclear membrane present. • Kingdom Protista or protistsKingdom Fungi or fungiKingdom Plantae or plantsKingdom Animalia or animals
Plantae Bacteria Fungi Algae Plants Two Kingdom System(Proposed by Aristotle)
Animalia Animals Protozoa Two Kingdom System
Problem with Aristotle’s Classification System: If it was green, it was a plant regardless of other features.
Five Kingdom System • Animalia • Plantae • Fungi • Protista • Procaryotae/Monera
Animalia • Multicellular • Heterotrophs
Plantae • Multicellular • Photoautotrophs
Fungi • Absorptive Chemoheterotrophs • Decomposers
Protista • Unicellular • Autotrophic or Heterotrophic
Three Domain System(Difference in rRNA and Cell Wall in Procaryotic Organisms) • Domain Eukaryae All Eukaryotic Organisms • Domain Bacteria True Bacteria and Cyanobacteria • Domain Archaea Ancient “Extreme” Bacteria
Modern Taxonomic Hierarchy Domain (Carl Woese) Kingdom Phylum/Division Class Order Family Genus Species